TUESDAY, May 24 (HealthDay News) -- Black people with multiple sclerosis are more likely to have vitamin D deficiencies than blacks who don't have the disease, a new study shows.
The study, published in the May 24 issue of the journal Neurology, also said the deficiency is due primarily to differences in climate and geography.
"MS is not as common in African-Americans as it is in whites, although the disease tends to be more severe in African-Americans," study author Dr. Ari J. Green, of the University of California, San Francisco, said in an American Academy of Neurology news release.
"We have known that vitamin D levels are associated with MS and that African-Americans are at increased risk for having low vitamin D levels, but little research has been done to look at vitamin D levels in African-Americans with MS," he said.
The study involved 339 people with MS and 342 people who did not have the disease. Researchers analyzed the blood vitamin D levels and the severity of the disease in each participant.
Since skin pigment acts as a filter of ultraviolet light, hence limiting the amount of vitamin D that can be produced by the body in response to sunlight, researchers also looked at the amount of UV exposure participants likely received based on where they lived, and the proportion of European genetic ancestry of each participant.
Vitamin D deficiency was found in 77 percent of the people with MS, compared to 71 percent of those without the disease. The people with MS were also exposed to a lower monthly UV index (average of 3.8) than those without MS (average of 4.8). Those with MS also lived an average of 1 degree of latitude farther north (about 69 miles) than those without the disease.
The researchers said the findings should open a dialogue between patients and their doctors about how much UV exposure they need, blood testing for vitamin D levels, and whether supplements would be a good choice.
"These findings may provide a mechanism to help explain how genes and the environment interact to produce MS," Green said.
For more on MS, visit the National Multiple Sclerosis Society.
-- Mary Elizabeth Dallas
SOURCE: American Academy of Neurology, news release, May 23, 2011
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